Blood manganese levels in Chinese children aged 0 to < 84 months: a nationwide cross-sectional study

Abstract Manganese (Mn) is an essential trace element with a biphasic, dose-dependent effect on neurodevelopment. Amidst the escalating risks of environmental Mn exposure, nationwide population-based reference values and the distribution of blood manganese levels (BMLs) in children remain undefined in China. To address this gap, we quantified BMLs in venous whole blood samples from 30,248 children aged 0 to < 84 months across 15 administrative divisions in China using inductively coupled plasma mass spectrometry. The overall geometric mean (GM) of BMLs was 13.39 µg/L (95% CI: 13.33–13.44). Spatially and demographically, significantly higher BMLs were identified in Western China, rural areas, and in girls (all P < 0.001). BMLs exhibited an age-dependent profile characterized by a sharp decline to a 6-month nadir, a late-infantile rebound, followed by a gradual decrease towards a homeostatic plateau from 24 months onward. The age-stratified population-based reference values (P2.5–P97.5) were 7.67–49.15 µg/L for infants aged 0 to < 6 months, 7.21–30.33 µg/L for those aged 6 to < 24 months, and 6.59–24.34 µg/L for children aged 24 to < 84 months. In conclusion, this study is the first nationwide large-scale epidemiological investigation of BMLs in young children in China, providing a comprehensive characterization of their overall distribution, age-dependent profile, and regional and demographic factors associated with BMLs. Furthermore, these findings provide a valuable baseline for future research on environmental Mn exposure and pediatric neurodevelopment.